1. Field of the Invention
The present invention relates to an electronic controlled air suspension system which is equipped with a high pressure reserve tank and a low pressure reserve tank for rapid control of the attitude of a vehicle.
2. Prior Art
A system having reserve tanks for supplying and discharging air to air springs, has been known in the prior art. The system is constructed of a closed air circuit to reduce both invasion of exterior dust or moisture and energy loss due to external liberation by reserving, in a high pressure reserve tank, the compressed air to supply the reserved compressed air to an air spring and by reserving the air used in the air spring in a low pressure reserve tank so that it may be used as the supply to the compressor. In this system, there also is a device to alarm when it detects insufficient air volume in the closed air circuit (as disclosed in Japan published examined patent publication No. 50-28589).
Another system is proposed in the prior art, which is constructed of an open air circuit for rapidly supplying an air spring under predetermined conditions with compressed air reserved in a high pressure reserve tank and for releasing the air used in the air spring externally so as to improve ride comfort of the vehicle (as disclosed in Japan published unexamined utility model application No. 58-112607).
Despite these facts, however, the electronic controlled air suspension system of the closed air circuit type can prevent the intrusion of exterior dust or moisture invasion and the energy loss but not completely the air leakage from the closed air circuit so that it cannot be safely used for an extended period of time. Whereas the open air circuit type is encountered with the problem of a great energy loss.
If, for example, the vehicle operates on a winding road so that it is frequently subjected to anti-roll controls for preventing its transverse inclinations, then the compressed air reserved in the high pressure reserve tank is consumed, and the air used in the air spring is reserved in the low pressure reserve tank. The frequent anti-roll controls would make it difficult to effect the rapid control of the attitude of the vehicle through the supply and discharge of the reserve tank because of the limited capacity of the reserve tank.